Aqueous hydraulic fluid



United States Patent Ofiice Edd-535d Patented Sept. 24, 1963 3,105,050 AQUEOUS HYDRAULIC FLUm Paul W. Fischer, Whittier, Calif., assignor to Union Oil Company of California, Los Angeles, Calif., a corporation of California No Drawing. Filed Nov. 13, 1959, Ser. No. 852,629 8 Claims. (Cl. 252-76) This invention relates to an aqueous hydraulic fluid composition, and more particularly concerns a hydraulic fluid composition suitable for use in driving hydraulic well pumps? it further relates to a concentrate composition adapted to being diluted with water to form a hydraulic fluid, and to a method for pumping wells with hydraulic pumps.

In certain oil fields, the crude oil is raised to the earths surface from its subterranean source by pumps of the hydraulic type. Such pumps, unlike the more familiar mechanized well pumps which are coupled by means of sucker rods to a source of mechanical power at the earths surface, are driven by a hydraulic fluid which is supplied to the pump under pressure via a conduit which extends through the well from a fluid source at the earths surface. A detailed description of this type of pump and its operation is given at pages 2894 et seq., of the 1957 edition of the Composite Catalog of Oil Field Equipment and Services. In some instances, the hydraulic fluid operates in a closed system, i.e., after passing through the driving section of the pump it is passed through a separate discharge conduit to the earths surface where it is repressured and returned to the pump. Ordinarily, however, it is more desirable to employ an open system in which the hydraulic fluid is discharged from the pump directly into the well bore or into the stream of crude oil discharged from the pump into the well tubing. Such system, of course, requires that the hydraulic fluid be a hydrocarbon oil which need not be separated from the crude, e.g., a portion of the crude itself, or an aqueous composition which can be separated from the crude and discarded along with the connate well water or brine. The use of a hydrocarbon oil, however, constitutes a major fire hazard; the hydraulic fluid is pumped down the well under high pressure, often in excess of 3,000 p.s.i., and at the elevated temperatures which are frequency encountered in well bores and in the vicinity of equipment located at the wellhead a leak or failure in the high pressure hydraulic line can result in a serious fire. Aqueous hydraulic fluids, on the other hand, have heretofore proved unsatisfactory from the standpoints of corrosion, lubricity, scale formation, and suitable viscosity.

It is an object of the present invention to provide hydraulic fluid compositions suitable for use in operating hydraulic well pumps as above described.

Another object is to provide non-inflammable aqueous hydraulic fluid compositions having satisfactory lubricity and viscosity characteristics, and being inhibited against corrosion and scale formation.

Another object is to provide concentrate compositions which can be shipped to the well site as such and there diluted with water to form aqueous hydraulic fluids having the aforementioned desirable characteristics.

A further object is to provide an improved method for operating hydraulic well pumps.

Other objects will be apparent from the following detailed description of the invention, and various advantages not specifically referred to herein will be apparent to those skilled in the art.

I have now found that the above objects and attendant advantages may be realized in compositions essentially comprising a major proportion of water, a minor proportion of a lubricating hydrocarbon oil, suflicient of an organic emulsifying agent to maintain the oil uniformly and stably dispersed in the water, and a minor proportion of a material which serves both as a corrosion inhibitor and as a scale inhibitor. As is hereinafter more fully explained, the compositions provided by the invention may optionally comprise a so-called bodying agent which serves to prevent leakage of the composition through the pump parts when operating at high pressures. The concentrate compositions provided by the invention differ from the foregoing only in that they contain less water; in some cases they may be water-free.

The aqueous component of the new compositions can be ordinary potable water or may be a typical oil field brine containing varying amounts of dissolved inorganic salts. Potable Water is, of course, preferred since its tendency to deposit scale and to induce corrosion is much less severe; however, one of the features of the invention lies in the fact that the particular non-aqueous components employed give very satisfactory results even when the aqueous phase contains relatively large amounts of dissolved inorganic salts. When oil field brine is used, it is of course apparent that suitable clarification or filtration steps must be employed to free the water from silt and sediment and avoid erosion of the pump.

The hydrocarbon oil component of the new compositions functions to impart lubricity to the composition. Although most hydrocarbons are lubricants and a typical crude oil separated from the field production can be employed, it is preferred to use a refined lubricating oil or lubricating oil distillate since the latter have better lubrication properties than crude oil and therefore can be employed in lower concentrations. A typical hydrocarbon lubricating oil found satisfactory in very low concentrations has a gravity of about 24 API and a viscosity at 100 F. of about 226 SSU.

The organic emulsifying agent of the new composition functions to uniformly disperse the hydrocarbon oil throughout the major aqueous phase. This emulsifying agent can be selected from any of the following Well known classes of emulsifiers: soap type emulsifiers, e.g., the alkali metal soaps of fatty acids, tall oil, caster oil,

linseed oil acids, naphthenic acids, as well as sulfonated derivatives thereof, such as sulfonated sperm oil soaps, and various sulfonic acids produced in the sulfuric acid refining of mineral oil, mahogany acids, etc. Non-soap type emulsifiers include the polyhydroxy alcohol mono esters, such as are formed by the esterification of glycerol or glycol with fatty acids, such as'oleic, lauric, ricinoleic, etc.; the polyalkylene oxide polyhydroxy alcohol mono fatty esters, such as polyoxyethylene sorbitan monolaurate, monostearate, or monooleate; and ester sulfonates of fatty oils and amides, such as sodium N-methyl- N-oleyl laurate; imidazolines of fatty acids, such as oleic, lauric and stearic imidazoline; etc.

The combination corrosion and scale inhibitor of the new composition is a polyalkylene polyamide of a long chain fatty acid. These compounds are described in U.S. Patent 2,598,213, and are obtained by reacting a polyalkylene polyamine with a long chain fatty acid under conditions to add the acyl radical of the acid and form a partially acylated product having at least one amino group. The reaction proceeds when the reactants, suitably proportioned, are mixed and heated to a temperature between about 156 C. to 325 C., while distilling water from the mixture. The reaction is usually complete in about 15 minutes to 3 hours depending on the temperature and identity of the reactants. Completion of the reaction is indicated when one mole of water has been distilled ofi for each amino group of the polyalkylene polyamine to be acylated. The polyethylene polyamines having the formula:

where x is between 1 to 6, when reacted with an acid having between about 12 and 22 carbons such as lauric, oleic, linoleic, stearic, erucic, etc., and high molecular weight fatty acids from animal or vegetable oils such as soybean oil, palm oil, coconut oil, etc., form a reaction product which has been found efiective in scale inhibition, where other conventional scale inhibitors such as phosphates, e.g., hexametaphosphate, were ineffectual.

The relative proportions of the various components of the new composition can be varied through wide ranges, the maximum amount of emulsifying agent and polyalkylene polyamide being generally limited by economics, particularly when an open system is employed and the power fluid is not recovered after use. Advantageously, it has been discovered that the new compositions are effective with extremely low concentrations of oil, dispersing agent and scale inhibitor.

The range of proportions of the components of the novel hydraulic fluid is as follows:

Volume percent Additives 0.003-30 Water Balance where the additives are present in the following relative proportions Volume percent Hydrocarbon oil 3080 Emulsifying agent l40 Polyalkylene polyamide l040 Generally the additives will be marketed as a concentrate to be mixed with water for use as the hydraulic fluid. Concentrate compositions having the aforementioned volumetric proportions of hydrocarbon oil, emulsifier, and polyalkylene polyamide are entirely satisfactory for this purpose. It is apparent that varied amounts of water, e.g., l to 50 percent can also be mixed in the concentrate composition so as to provide a water emulsion suitable for direct addition to the main body of water employed for the hydraulic fluid.

The following examples illustrate typical formulations of the hydraulic fluid compositions provided by the invention.

Example I Component: Volume percent Lubricating oil (200 SSU at 100 F.) 0.003 Sulfonated sperm oil soap 0.003 Reaction product of tetraethylene pentamine with mixed fatty acids of soybean oil 0.003

Water Balance This composition is suitably prepared by adding a concentrate mixture comprising equal amounts of lubricating oil, sulfonated soap andscale inhibitor to water at the rate of about 3 pints per 100 barrels of water. The concentrate can be added to the water at any suitable point; however, it is preferred to add it prior to pressurization by the surface pump at the Well head so as to obtain better dispersion and to reduce the Wear in this pump. This is suitably accomplished by mixing the chemicals into the water supply tank or by continuously injecting them into the suction side of the pump. When the additives are in the form of a non-aqueous concentrate, they are suitably pre-mixed with a slight amount of water before addition to the main body of water so as to obtain better dispersion in the final hydraulic fluid.

and about +25, or even higher.

Example 1" Volume percent Lubricating oil (200 SSU at F.) 10.0

Glycol mono-oleate 2.0 Reaction product of tetraethylene pentamine with oleic acid 5.0

Water Balance Example H1 Reduced crude oil 0.05 Heptadecyl im-idazoline 0.01 Reaction product of triethylene tetramine with mixed castor oil fatty acids 0.05 Water Balance Example I V Lubricating oil 1.0K. Polyoxyethylene sorbitan monolaurate 0.1 Reaction product of diethylene triamine with soybean fatty acids 0.1 Water Balance Example V Lubricating oil 0.005 Petroleum sulfonates 0.002 Reaction product of pentaethylene hexamine with tall oil acids 0.001 Water Balance Example VI Crude oil 2.5 Sodium soaps of mixed linseed acids 0.05 Reaction product of ethylene d-iamine with soybean fatty acids 0.01 Water Balance Any of the above compositions may be prepared in concentrate form simply by omitting all or part of the water.

Although the compositions described above comprising a major amount of water and minor amounts of oil, emulsifier and scale inhibitor are eminently satisfactory for use inrelatively shallow wells, they are less satisfactory for use in wells of greater than about 5000 feet in depth. At such depths, the hydraulic fluid passes through the well pump at pressures of about 2500 psi. or greater, and considerable leakage occurs through the pump. In accordance with a modification of the invention, hydraulic fluid compositions suitable for use vatsuch high pressures are obtained by adding a bodying agent to any of the compositions described above. Such bodying agent comprises a rosin soap obtained by saponifying rosin with an alkali-metal hydroxide, erg, sodium or potassium hydroxide, by procedures well known in the art and in a manner so that the reaction is only partially complete and the saponified product contains from about 1 to about 15 percent of free unsaponified resin acids.

Rosin in which the resin acids have been isomerized or disproportionated is preferred in forming the alkalimetal soaps. The isomerization of rosin is well known in the naval stores art, and may be effected. in various ways to obtain modified rosin products which vary somewhat in their physical and chemical properties depend ent upon the temperature and length of the heat treatment. In general, temperatures range from 250 C. to about 350 C., and the length of the healing period is sufficient to raise the specific rotation of the rosin from its original negative value to a value between about +5 The product, while closely resembling the original rosin in appearance and ease of :saponification, is considerably altered chemically, as evidenced by its specific rotation, increased dehydroabietic acid content and lower iodine number. Rosin oils, i.e., unsaponifiable bodies, are also formed from decarboxylation which occurs when higher temperatures E3 and longer heating periods are employed. A product obtained by the potassium hydroxide saponification of rosin isomerized by heat treatment between 250 C. and 350 C. is commercially available under the trade name Dresinate 90.

The rosin can also be modified by heating at relatively low temperatures in the presence of hydrogenation catalysts as described in U.S. Patent 2,154,629. In the absence of added hydrogen, disproportionation occurs, i.e., simultaneous dehydrogenation and hydrogenation, to form dihydroabietic and dehydroabietic acid and their analogues, and the resulting product is referred to as a disproportionated rosin. Some decarboxylation also occurs at high temperatures. A product which is obtained by the sodium hydroxide sapom'fication of a disproportionated rosin obtained by heating rosin at a temperature 'of about 225300 C. for 15-60 minutes in contact with a hydrogenation catalyst is commercially available under the trade name Dresinate 731.

The saponified rosin product can be added directly to the aqueous hydraulic liquid, but a somewhat greater improvement is obtained if it is added as a pro-mixed concentrated dispersion in water or in a water-so1uble medium such as alcohols, ketones, alcohol ethers, glycols, etc. The quantity of saponified rosin added to the aqueous hydraulic fluid varies somewhat, depending on the type of rosin soap arid on the hydraulic fluid pressure. In general, the rosin soaps are employed at concentrations between about 0.1 to 5.0 grams per gallon of hydraulic fluid, with the most effective range between about 0.3 to 1.0 gram per gallon. For convenience in marketing and to eliminate a second addition step in the field, the rosin soap can be added to the aforementioned concentrate of oil, emulsifying agent and polyalkylene amide in the range of 0.5 to 5 parts per part of concentrate.

In addition to the aforementioned additives, the aqueous hydraulic fluid can contain varying amounts of extreme pressure agents containing halogens, sulfur, phosphorus or combinations thereof in the manner well known in the art. Supplementary corrosion inhibitors can also be added to the fluid when necessary in accordance with the practice in the art without departing from the scope of the invention.

The invention will be more completely described by the following examples:

Example VII A hydraulic pump in a Well 7,800 feet below the surface and at a pressure of about 3,000 psi. was operated with brine separated from the production fluids. This pump failed three days after the start of the test.

The pump was then repaired, and the test was repeated with the continuous addition of a lubricating mixture comprising a 4 to 1 mixture of lubricating oil and sulfonated sperm oil soap at the rate of 0.002 gallon per barrel of the brine used as the hydraulic fluid. This pump failed after six days due to scale deposits on the engine.

After the scale deposits were removed, the pump was again operated with brine containing the same amount of the lubricating mixture to which 0.005 percent of hexametaphosphate scale inhibitor had been added. Within 14 days the pump efliciency had decreased to 60 percent due to scale deposits which were found to be magnesium and calcium phosphates.

After removal of the scale deposits, the pump was operated with a hydraulic fluid which was identical with that employed in the preceding test except that the hexarnetaphosphate scale inhibitor was replaced by 0.005 percent of a 20 weight percent aqueous solution of a polyethylene polyamide product from the reaction of tetraethylene pentamine and a fatty acid from soybean oil. The test was repeated several times for an average run length of about 16 days without scale formation.

Example V111 To evaluate the present bodying agents, a hydraulic pump was operated with an aqueous hydraulic liquid containing varying amounts of additives, and the leakage in milliliters per minute was measured. Wood rosin soap, Dresinate 90, and Dresinate 731 showed the greatest rate of decrease in water loss at concentrations up to about 1.0 gram per gallon of fluid. About percent decrease in fluid loss was observed with 0.5 gram per gallon of rosin soap, about percent decrease was observed with 1.0 gram per gallon of fluid of Dresinate 90, and about 65-75 percent decrease was observed with 1.0 gram or" Dresinate 731 per gallon of fluid.

I claim:

1. An aqueous hydraulic fluid comprising at least 60 volume percent water, between about 0.001 and about 30 volume percent of a liquid hydrocarbon oil emulsified in said water, between about 0.001 and about 10 volume percent of an oil-in-water emulsifier, sufficient to ernulsify said oil in said Water, the remainder of said hydraulic fluid comprising said water and between about 0.1 and about 5 .0 grams per gallon of an alkali metal saponified rosin, said hydraulic fluid being free of silt and suspended solid matter.

2. The method of operating hydraulic equipment which comprises supplying to said equipment an aqueous hydraulic fluid comprising between about 0.001 and about 30 volume percent of a liquid hydrocarbon oil emulsified in water, between about 0.001 and about 10 volume percent of an oil-in-water emulsifier, sufficient to emulsify said oil in said water, the remainder of said hydraulic fluid comprising said water and between about 5 .0 grams per gallon of an mkali metal saponified rosin, said hydraulic fluid being free of silt and suspended solid matter.

3. A composition of matter dispersible in water to form a hydraulic fluid comprising between about 30 and about 80 volume percent of a hydrocarbon oil, between about 10 and about 40 percent of an oil-in-water emulsifier, between about 10 and about 40 volume percent of a corrosion and scale inhibitor comprising the partially acylated reaction product having at least one amino group, said product being obtained by the reaction of a polyalkylene polyamine with a 12 to 22 carbon fatty acid, said fatty acid being in an amount insufficient to react with all the amino groups of said polyalkylene polyamine so as to impart corrosion inhibiting properties to said reaction product, and between about 0.5 and 5 volume parts of a saponified rosin per volume of said hydrocarbon oil, emulsifier arid reaction product.

4.- A composition as defined by claim 3 wherein said emulsifier is an alkali metal soap of a fatty acid.

5. A composition as defined by claim 3 wherein said amide is the reaction product of tetraethylene pentamine and soybean fatty acids.

6. A composition containing 1 volume of the composition defined in claim 3 and between about 0.01 and 1 volume of water.

7. An aqueous hydraulic fluid consisting of between about 0.003 and about 30 volume percent of the composition defined by claim 3 and water, said hydraulic fluid being free of silt and suspended solid matter.

8. The method of producing oil from a subterranean oil well wherein an oil-containing effluent is raised to the surface by a hydraulically operated pump, which method comprises employing as the hydraulic power fluid the aqueous composition defined by claim 7.

References Cited in the file of this patent UNITED STATES PATENTS 2,568,876 White et a1. Sept. 25, 1951 2,598,213 Blair May 27, 1952 2,697,692 Salathiel Dec. 21, 1954 2,754,265 Hoeppel July 10, 1956 2,967,831 Hemmer Tan. 10, 1961 

1. AN AQUEOUS HYDRAULIC FLUID COMPRISING AT LEAST 60 VOLUME PERCENT WATER, BETWEEN ABOUT 0.001 AND ABOUT 30 VOLUME PERCENT OF A LIQUID HYDROCARBON OIL EMULSIFIELD IN SAID WATER, BETWEEN ABOUT 0.001 AND ABOUT 10 VOLUME PERCENT OF AN OIL-IN-WATER EMULSIFIER, SUFFICIENT TO EMULSIFY SAID OIL IN SAID WATER, THE REMAINDER OF SAID HYDRAULIC FLUIF COMPRISING SAID WATER AND BETWEEN ABOUT 0.1 AND ABOUT 5.0 GRAMS PER GALLON OF AN ALKALI METAL SAPONIFIED ROSIN, SAID HYDRAULIC FLUID BEING FREE OF SILT AND SYSPENDED SOLID MATTER. 